The smashed Iraqi laboratory may once have produced a million veterinary vaccines a year, as Saddam Hussein's regime claimed. But in 1998 this site outside Baghdad was ground zero in United Nations efforts to erase Iraq's biological weapons program.

Armed with the most intrusive arms-control mandate in history, the UN Special Commission (UNSCOM) destroyed whatever it could find of Iraq's chemical, biological, nuclear, and long-range missile programs. By some estimates, the seven-year mission disarmed the regime by up to 95 percent.

But what is left? What weapons has Iraq been able to reassemble since UNSCOM departed in late 1998? Those uncertainties lie at the heart of the current debate over possible US military action against Iraq. The key question is this: Could renewed, unfettered weapons inspections contain Iraq and avert war, as many weapons experts say? Or, as the White House argues, is military action the only course that remains?

In the Bush administration's most forceful statement on Iraq yet, Vice President Dick Cheney on Monday argued for a pre-emptive US strike, saying that Baghdad was "very busy enhancing" its capabilities for weapons of mass destruction; that Iraq will acquire nuclear weapons "fairly soon;" and that a return of weapons inspectors "would provide no assurance whatsoever."

"The risks of inaction," Mr. Cheney said, "are far greater than the risk of action."

But many analysts  including some ranking congressmen who receive classified intelligence briefings  say they have seen no new evidence to confirm those claims. And even key former UNSCOM officials disagree on what danger Iraq may pose today.

In a search for answers, officials are drawing on the lessons of UNSCOM. In 1991, Iraq declared only a fraction of missile and chemical capabilities, denied any significant nuclear capability  and denied the existence of its entire biological program, which 1998 US figures show created 22,457 gallons of anthrax and 100,393 gallons of botulinum toxin alone.

UNSCOM records show that by 1998 it had accounted for or destroyed 817 of 819 Scud missiles, but could not trace seven Iraqi-made missiles that had been listed as operational at the end of the Gulf War.

Nearly 39,000 chemical munitions and more than 3,000 tons of agents and precursors were destroyed. But never found were 500 mustard-gas shells, 25 "special warheads," 150 aerial bombs, and several hundred tons of chemicals for the nerve agent VX. Expert committees in 1998 found Iraq's so-called "final" disclosures to be "flawed."

While such leftovers are a "marginal" amount of material, says Rolf Ekeus, the Swedish former director of UNSCOM, "there is considerable risk they can produce chemical weapons.

"I have very serious concerns about missiles," says Mr. Ekeus, now head of the Stockholm International Peace Research Institute. "We don't know how much they smuggled in there. My theory is that they have built production lines."

Just hours before a three-day American bombing assault in late 1998, the UN withdrew its inspectors. Mr. Hussein has never allowed them to return.

Getting weapons inspectors back into Iraq, says Ekeus, is the only effective solution  a view echoed by Scott Ritter, a former US marine who worked for UNSCOM from 1991 to 1998, leading the team that unraveled Iraqi concealment efforts.

Iraq was 90 to 95 percent disarmed in 1998, Mr. Ritter says, and little has changed since then. "Where is the evidence? All we hear from the administration is that, because Saddam gassed the Kurds in 1988, he has weapons of mass destruction," Ritter says. "But we destroyed those chemical factories, and we destroyed the biological facilities. Even if he hid some warheads, they would have degenerated by now."

Ritter estimates that by 1998, Iraq could have reconstituted small mustard-chemical agents in eight weeks to two months. It could also produce "small-scale" Sarin nerve agent within four months and have lab-scale VX nerve agent in six to eight months  all undetectable at that scale. On the biological side, weaponizing to kill many people was out of reach. "What Iraq had in 1991 wasn't a [biological] weapon, it was a large chunk of metal with some sludge in it," Ritter says. "The only way it was going to kill you was if it landed on your head."

Iraq is capable of breaking out of the 93-mile missile range  the limit imposed by the Gulf War cease-fire agreement  but would not be able to test without detection. As for nuclear capabilities, Ritter says: "Forget it. That was where Iraq was most thoroughly disarmed."

Some former UNSCOM officials are alarmed, however. Terry Taylor, a British senior UNSCOM inspector from 1993 to 1997, says the figure of 95 percent disarmament is "complete nonsense because inspectors never learned what 100 percent was. UNSCOM found a great deal and destroyed a great deal, but we knew [Iraq's] work was continuing while we were there, and I'm sure it continues," says Mr. Taylor, now head of the Washington office of the London-based International Institute of Strategic Studies. In 1995, Iraq was caught importing missile parts via Jordan, for example, and hiding them on the bottom of the Tigris River.

Though the nuclear file is usually the first to be dismissed as virtually "closed," Taylor says dismantlement efforts were incomplete. Iraq was working to master simultaneous timing of explosions, "and even at its most intrusive, UNSCOM could never have found that." The nuclear program was Iraq's "most prized, and given the nature of the regime, I don't think they have given up on that objective ... I think they could have nuclear weapons very, very quickly, if they got hold of fissile material  it could be a matter of a few months." The Iraqis "are the greatest [people] in the world at hiding these things from inspectors," he adds. "My view is, we don't need any more evidence [before taking action]."

But Toby Dodge, an Iraq specialist at the Royal Institute for Strategic Studies in London, says little solid evidence has emerged that Iraq had been on any recent "shopping spree" such as the one that took place in the 1980s, when the US and UK helped arm Iraq against Ayatollah Khomeini's Iran.

Underlining the dearth of current evidence on Iraq, a dossier of alleged Iraqi violations, collated by British Prime Minister Tony Blair's office last spring, has not been made public. Sources familiar with its charges, Mr. Dodge says, indicate that it was "not convincing at the time" and was based largely on unreliable accounts from defectors. Iraq's main procurement network, Dodge adds, has also been "rolled up."

"Nobody has shown a red flag to us yet," says Amin Tarzi, an Iraq specialist at the Center for Non-Proliferation Studies in Monterey, Calif., which runs a project to chart all public information about Iraq's illicit programs. "The scariest thing about Iraq is that they have the know-how. But the point is: We don't know what is happening."

New weapons inspection teams to replace UNSCOM, led by former UN atomic energy agency chief Hans Blix, have yet to set foot in Iraq. Ensuring that those inspectors are effective would "require that the US put all its effort into it, and line up Russia, France, and China" on the UN Security Council, Ekeus says.

"Saddam Hussein is married to these weapons, which will make him a major player of regional and even global significance," Ekeus says. "Without them, he is, at most, a local thug."